Towing vehicles, such as tractor trucks or semi-tractors and the like, are equipped with fifth wheel hitches which receive and engage the kingpins of trailers. The fifth wheel is positioned on the back of the tractor truck and features a top plate having a central throat equipped with a latching mechanism which engages the kingpin. The throat may be, for example, provided with an open end facing the rear of the truck. The kingpin extends downward from the underside of the leading end portion of the trailer. The engagement of the trailer kingpin by the fifth wheel is the primary means by which the trailer is pivotally connected to the tractor.
Terminal tractors, which may be tractor trucks or other vehicles equipped with a fifth wheel, are typically used to move trailers within a cargo yard, warehouse facility, or intermodal facility, as opposed to moving trailers on public roads. Terminal tractors serve a function in the trucking industry that is similar to switch engines or shunting locomotives in the railroad industry. The fifth wheels of terminal tractors are therefore subject to much more frequent hitching and unhitching operations than highway tractors. As a result, a need exists for fifth wheel locking mechanisms for terminal tractors, and similar applications, that are very robust, reliable and quick and easy to hitch and unhitch. It is also desirable for such fifth wheels to prevent, or at least minimize, false locking cases.